The present invention relates generally to fluid systems, and more particularly to a pressurization system for a gas turbine engine.
There are a variety of known gas turbine engine configurations, including two-spool, high-bypass engines. Such an engine typically includes a high pressure spool, a combustion system and a low pressure spool disposed within an engine case to form a generally axial, serial flow path about the engine centerline. The high pressure spool includes a high pressure turbine, a high pressure shaft extending axially forward from the high pressure turbine, and a high pressure compressor connected to a forward end of the high pressure shaft. The low pressure spool includes a low pressure turbine, which is disposed downstream of the high pressure turbine, a low pressure shaft, which typically extends coaxially through the high pressure shaft, and a low pressure compressor connected to a forward end of the low pressure shaft, forward of the high pressure compressor. A fan is also connected to the low pressure spool, forward of the low pressure compressor. The combustion system is disposed between the high pressure compressor and the high pressure turbine and receives compressed air from the compressors and fuel provided by a fuel injection system. A combustion process is carried out within the combustion system to produce high energy exhaust gases to produce thrust and turn the high and low pressure turbines, which drive their respective compressors and the fan to sustain the combustion process.
Because there are rotating components within the stationary components of a gas turbine engine, bearings are installed to promote smooth and efficient operation. Traditionally, the bearings are bathed in lubricating oil that is pumped into and scavenged out of the inside of the bearing compartment. The exterior of the bearing compartment is pressurized by an air buffer system to inhibit oil from inside of the compartment leaking outside of the compartment. There may be transient operational conditions where the air buffer system is not providing sufficient pressure to inhibit leakage from the bearing compartment.